1. Field of the Invention
The present invention relates to an input device and a method of producing an input device and, more specifically, relates to a thin input device in which bubbles do not form in a light-transmissive region.
2. Description of the Related Art
Today, light-transmissive input devices are used as display units in portable electronic apparatuses to allow an operator to input coordinates by directly operating menu items and objects of a display image with a finger. Such an input device is disposed over a display device in an electronic apparatus; therefore, the input device should be thin and having excellent visibility when a user views a display image on the display device.
FIG. 12 illustrates a known input device 101 described in Japanese Unexamined Patent Application Publication No. 2005-173970. The input device 101 includes an upper transmissive substrate 131 and a lower transmissive substrate 132 with a spacer 138 and a gap provided therebetween. An upper transparent conductive film 133 and a lower transparent conductive film 134 are respectively disposed on the opposing surfaces of the upper transmissive substrate 131 and lower transmissive substrate 132. The upper transmissive substrate 131 is a flexible film. Thus, the upper transparent conductive film 133 and the lower transparent conductive film 134 contact each other when a desired position on an input surface is pushed. The known input device 101 is a resistive touch panel, which reads a change in resistance to detect the input position coordinate.
An upper printing circuit 135 for connecting the upper transparent conductive film 133 with an external circuit is disposed on the periphery of upper transparent conductive film 133, and a lower printing circuit 136 is disposed on the periphery of the lower transparent conductive film 134. The upper printing circuit 135 and the lower printing circuit 136 are made of a conductive paste composed of a conductive metal filler, such as silver or copper. Since the input device 101 includes light-transmissive substrates, the upper printing circuit 135 and the lower printing circuit 136 are visible from the outside.
In the known input device 101 illustrated in FIG. 12, a decorative printing sheet 141a is attached to the input-surface side of the upper transmissive substrate 131 with an adhesive layer 151. A decorative printing layer 141b on the periphery of the decorative printing sheet 141a prevents the upper printing circuit 135 and the lower printing circuit 136 from being visible from the outside.
By providing the decorative printing sheet 141a, a frame, which is typically referred to as “bezel,” covering the upper printing circuit 135 and the lower printing circuit 136 is no longer required. Therefore, the input-surface side of the frame of the input device 101 does not have an unlevel section, and thus, the external appearance can be improved. Since the decorative printing sheet 141a is thinner than the frame, the thickness of the input device 101 can be reduced.